---
title: schedules
sidebarTitle: schedules
---

# `prefect.client.schemas.schedules`



Schedule schemas


## Functions

### `is_valid_timezone` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L29" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
is_valid_timezone(v: str) -> bool
```


Validate that the provided timezone is a valid IANA timezone.

Unfortunately this list is slightly different from the list of valid
timezones we use for cron and interval timezone validation.


### `is_schedule_type` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L333" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
is_schedule_type(obj: Any) -> TypeGuard[SCHEDULE_TYPES]
```

### `construct_schedule` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L337" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
construct_schedule(interval: Optional[Union[int, float, datetime.timedelta]] = None, anchor_date: Optional[Union[datetime.datetime, str]] = None, cron: Optional[str] = None, rrule: Optional[str] = None, timezone: Optional[str] = None) -> SCHEDULE_TYPES
```


Construct a schedule from the provided arguments.

**Args:**
- `interval`: An interval on which to schedule runs. Accepts either a number
or a timedelta object. If a number is given, it will be interpreted as seconds.
- `anchor_date`: The start date for an interval schedule.
- `cron`: A cron schedule for runs.
- `rrule`: An rrule schedule of when to execute runs of this flow.
- `timezone`: A timezone to use for the schedule. Defaults to UTC.


## Classes

### `IntervalSchedule` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L46" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


A schedule formed by adding `interval` increments to an `anchor_date`. If no
`anchor_date` is supplied, the current UTC time is used.  If a
timezone-naive datetime is provided for `anchor_date`, it is assumed to be
in the schedule's timezone (or UTC). Even if supplied with an IANA timezone,
anchor dates are always stored as UTC offsets, so a `timezone` can be
provided to determine localization behaviors like DST boundary handling. If
none is provided it will be inferred from the anchor date.

NOTE: If the `IntervalSchedule` `anchor_date` or `timezone` is provided in a
DST-observing timezone, then the schedule will adjust itself appropriately.
Intervals greater than 24 hours will follow DST conventions, while intervals
of less than 24 hours will follow UTC intervals. For example, an hourly
schedule will fire every UTC hour, even across DST boundaries. When clocks
are set back, this will result in two runs that *appear* to both be
scheduled for 1am local time, even though they are an hour apart in UTC
time. For longer intervals, like a daily schedule, the interval schedule
will adjust for DST boundaries so that the clock-hour remains constant. This
means that a daily schedule that always fires at 9am will observe DST and
continue to fire at 9am in the local time zone.

**Args:**
- `interval`: an interval to schedule on
- `anchor_date`: an anchor date to schedule increments against;
if not provided, the current timestamp will be used
- `timezone`: a valid timezone string


**Methods:**

#### `model_validate_list` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/_internal/schemas/bases.py#L56" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
model_validate_list(cls, obj: Any) -> list[Self]
```

#### `reset_fields` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/_internal/schemas/bases.py#L85" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
reset_fields(self: Self) -> Self
```

Reset the fields of the model that are in the `_reset_fields` set.

**Returns:**
- A new instance of the model with the reset fields.


#### `validate_timezone` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L85" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
validate_timezone(self)
```

### `CronSchedule` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L100" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Cron schedule

NOTE: If the timezone is a DST-observing one, then the schedule will adjust
itself appropriately. Cron's rules for DST are based on schedule times, not
intervals. This means that an hourly cron schedule will fire on every new
schedule hour, not every elapsed hour; for example, when clocks are set back
this will result in a two-hour pause as the schedule will fire *the first
time* 1am is reached and *the first time* 2am is reached, 120 minutes later.
Longer schedules, such as one that fires at 9am every morning, will
automatically adjust for DST.

**Args:**
- `cron`: a valid cron string
- `timezone`: a valid timezone string in IANA tzdata format (for example,
America/New_York).
- `day_or`: Control how croniter handles `day` and `day_of_week`
entries. Defaults to True, matching cron which connects those values using
OR. If the switch is set to False, the values are connected using AND. This
behaves like fcron and enables you to e.g. define a job that executes each
2nd friday of a month by setting the days of month and the weekday.


**Methods:**

#### `model_validate_list` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/_internal/schemas/bases.py#L56" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
model_validate_list(cls, obj: Any) -> list[Self]
```

#### `reset_fields` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/_internal/schemas/bases.py#L85" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
reset_fields(self: Self) -> Self
```

Reset the fields of the model that are in the `_reset_fields` set.

**Returns:**
- A new instance of the model with the reset fields.


#### `valid_cron_string` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L143" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
valid_cron_string(cls, v: str) -> str
```

#### `valid_timezone` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L138" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
valid_timezone(cls, v: Optional[str]) -> Optional[str]
```

### `RRuleSchedule` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L168" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


RRule schedule, based on the iCalendar standard
([RFC 5545](https://datatracker.ietf.org/doc/html/rfc5545)) as
implemented in `dateutils.rrule`.

RRules are appropriate for any kind of calendar-date manipulation, including
irregular intervals, repetition, exclusions, week day or day-of-month
adjustments, and more.

Note that as a calendar-oriented standard, `RRuleSchedules` are sensitive to
to the initial timezone provided. A 9am daily schedule with a daylight saving
time-aware start date will maintain a local 9am time through DST boundaries;
a 9am daily schedule with a UTC start date will maintain a 9am UTC time.

**Args:**
- `rrule`: a valid RRule string
- `timezone`: a valid timezone string


**Methods:**

#### `from_rrule` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L201" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
from_rrule(cls, rrule: Union[dateutil.rrule.rrule, dateutil.rrule.rruleset]) -> 'RRuleSchedule'
```

#### `model_validate_list` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/_internal/schemas/bases.py#L56" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
model_validate_list(cls, obj: Any) -> list[Self]
```

#### `reset_fields` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/_internal/schemas/bases.py#L85" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
reset_fields(self: Self) -> Self
```

Reset the fields of the model that are in the `_reset_fields` set.

**Returns:**
- A new instance of the model with the reset fields.


#### `to_rrule` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L250" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
to_rrule(self) -> Union[dateutil.rrule.rrule, dateutil.rrule.rruleset]
```

Since rrule doesn't properly serialize/deserialize timezones, we localize dates
here


#### `valid_timezone` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L308" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
valid_timezone(cls, v: Optional[str]) -> str
```

Validate that the provided timezone is a valid IANA timezone.

Unfortunately this list is slightly different from the list of valid
timezones we use for cron and interval timezone validation.


#### `validate_rrule_str` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L197" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
validate_rrule_str(cls, v: str) -> str
```

### `NoSchedule` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/client/schemas/schedules.py#L324" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

**Methods:**

#### `model_validate_list` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/_internal/schemas/bases.py#L56" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
model_validate_list(cls, obj: Any) -> list[Self]
```

#### `reset_fields` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/_internal/schemas/bases.py#L85" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
reset_fields(self: Self) -> Self
```

Reset the fields of the model that are in the `_reset_fields` set.

**Returns:**
- A new instance of the model with the reset fields.

